Endoscopy plays an important role in the diagnosis and management of digestive diseases. It is estimated that more than 20 million endoscopic procedures are performed annually in the United States. The Clinical Outcomes Research Initiative (CORI) was developed in the 1990's to collect endoscopy data from diverse practice settings with goal of measuring utilization and outcomes to improve the practice of endoscopy. The consortium includes endoscopists in 70 practices, who use a computer to generate endoscopy reports which are sent electronically to a central data repository. The repository receives more than 260,000 reports annually. The consortium has completed both descriptive analyses of endoscopy practice and prospective studies. CORI has been funded by NIDDK since 1999, and produced 47 manuscripts in peer-reviewed journals covering a broad range of topics in endoscopy, and received other federal and foundation grants to support specific research projects. The specific aim of the current proposal is to use the existing endoscopic data repository and consortium to perform research which will improve the quality of endoscopic practice. There are three primary themes. Theme 1: analysis of practice. These studies will identify opportunities for improving practice by first identifying current practice patterns, and measuring key endoscopic outcomes. We will determine best practices and changes in practice over time. Theme 2: improving quality of endoscopic practice. We will measure endoscopic quality indicators and study the impact of interventions designed to achieve best practices. These interventions will include embedding educational guidelines into computer software and providing personal quality assurance reports to individual providers. Theme 3: This unique data repository will be a resource to the research and public health community in the United States and abroad.